Polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic pollutants which pose a threat to both human health as well as the biosphere generally. These compounds are contaminants of herbicides, such as Agent Orange, and are also generated as by-products in a variety of industrial chemical processes, as well as in the course of combustion or incineration of other polychlorinated organics, such as plastics and polychlorinated biphenyls (PCB). In view of the extensive use or occurrence of such processes, dioxins and dibenzofurans are widespread in the environment. Now that the harmful nature of these materials has become fully recognized, it has become a matter of high priority to address the issue. An important, nontrivial first step is to identify sites of pollution, which requires a simple, economical, and rapid test for detecting the presence of these compounds in samples taken from soils, human or animal tissues, as well as foodstuffs.
An important aspect of a desirable test procedure relates to specificity. There are a large number of isomers both PCDD's and PCDF's, as well as PCB's, which vary in toxicity from very highly toxic to lesser toxicities, but which are also chemically similar to other, relatively harmless compounds. A second aspect of the problem is that the most toxic isomers of these compounds in the environment, i.e., 2,3,7,8-tetrachlorodibenzo-p-dioxin, is harmful in very small amounts, and is capable of being concentrated as it moves through food chains. Hence, a desirable test must be capable of detecting the presence of these harmful substances in very low concentrations. Chemical analysis of soil samples for contamination is also hampered by several other factors: (1) dioxins bind tightly to soil and show negligible solubility in water, and (2) the multiplicity of isomers and related chemical contaminants make quantitative assay by conventional gas chromatographic and mass spectrometric methods costly and time consuming. The costs and turn-around time preclude detailed sampling of an area to determine the extent of contamination, and require sophisticated centralized laboratories, unsuited for field monitoring of this health hazard.